JP2007175861A - Inspection method for micro-structure and micro-machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inspection method, performing an inspection for the process confirmation for a structure in a micro-machine, the inspection for electric characteristic and the inspection for mechanical characteristic in non-contact state. <P>SOLUTION: In this inspection method for the structure including a first conductive layer, a second conductive layer provided parallel to the first conductive layer and a sacrifice layer or a space part provided between the first conductive layer and the second conductive layer, an antenna is connected to the structure, the power is supplied to the structure by wireless through the antenna, and an electromagnetic wave generated from the antenna is detected as the characteristic of the structure. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a method for inspecting a structure included in a micromachine manufactured by surface micromachining, and a micromachine and a structure manufactured by applying the inspection method.

The micromachine is also called MEMS (Micro Electro Mechanical System) or MST (Micro System Technology), and is a comprehensive combination of a micro mechanical structure (called a micro structure or simply a structure) and an electric circuit. Refers to the system.
Micromachines include bulk micromachines that produce structures using crystal anisotropy of silicon substrates and surface micromachines that produce three-dimensional structures by stacking thin films on various substrates. In either of these methods, a structure having a certain function and a peripheral circuit (electric circuit) are integrated on-chip or on-package.
Here, on-chip refers to manufacturing an electric circuit and a structure having semiconductor elements on the same substrate, and on-package refers to an electric circuit and a structure manufactured on separate substrates in one package. In the form of the final product.

A structure manufactured by surface micromachining or bulk micromachining technology and a peripheral circuit manufactured by conventional LSI technology have different causes of yield reduction. Therefore, the yield of the micromachine having both of them is the product of the yield of the structure and the yield of the electric circuit, whether it is on-chip or on-package, so it is difficult to increase productivity.

In particular, the structure has a low yield. There are various reasons for this. For example, a substrate that has undergone process checks such as film thickness and etching rate cannot be returned to the process and must be discarded, or until the structure is mounted on the final product. This is because it has a problem that it is difficult to evaluate whether or not it operates normally. Various studies have been conducted to solve these problems (see, for example, Patent Documents 1 and 2).
JP 2005-43514 A Japanese Patent No. 3549105

Patent Document 1 proposes a device measurement method and an inspection method that accurately determine whether or not a structure is deformed by internal stress and whether or not characteristics set at the time of design can be obtained. Patent Document 2 proposes a method for inspecting the mechanical characteristics of an actuator using the frequency characteristics of the structure.

With the above technique, the structure can be inspected by microscopic observation, electrical property measurement, etc., and the substrate is not discarded after the inspection. However, for example, the inspection disclosed in Patent Document 1 is performed on the inspection pattern, and the structure to be manufactured cannot be inspected. Moreover, the inspection of the above-mentioned Patent Document 2 can be performed only after the fabrication of the structure is completed, and inspection for process confirmation cannot be performed.

In general, the process confirmation inspection and electrical characteristic inspection for the total number of structures fabricated on the substrate require sophisticated technology and expensive equipment because the structure and mechanism are complicated. It is very time consuming and not easy to implement. In addition, the measurement of electrical characteristics is performed by bringing a prober's needle into contact with the substrate. However, unlike a general semiconductor element, this increases the risk of destroying a structure having a three-dimensional structure.

In addition, when an inspection is performed with a prober in contact with the probe, the substrate is contaminated by peeling off the layer of the contacted part or dropping the dust.

When a contact-type inspection is performed during a general semiconductor element manufacturing process, the substrate is always washed and then returned to the process. However, a micromachine having a space portion and having a three-dimensional structure cannot be cleaned because the structure is destroyed.

Further, the space portion included in the structure is formed by removing the sacrificial layer under the structure layer by etching. If the structural layer is made of a material that is opaque to visible light (mostly opaque because of the use of metal for the structural layer), whether or not the sacrificial layer has been completely removed by sacrificial layer etching. It cannot be inspected using an easy means such as an optical microscope. If inspection is to be performed, the substrate is divided after the sacrificial layer etching, and the cross section is observed with an SEM or the like. However, even if it is determined by this inspection whether or not the sacrificial layer has been completely removed, it is impossible to return the already divided substrate to the process.

For this reason, when the structure and the peripheral circuit are on-packaged, the peripheral circuit is selected by inspection so that the peripheral circuit operates reliably. 100% inspection has been performed for the first time in the final inspection of NO. This is a cause of greatly reducing the productivity of the micromachine.

In view of the above problems, an object of the present invention is to provide an inspection method capable of easily performing non-contact inspection of inspection of a structure of a micromachine structure, inspection of electric characteristics, and inspection of mechanical characteristics. It is another object of the present invention to provide an inspection method capable of performing a process confirmation inspection, an electrical property inspection, and a mechanical property inspection for all structures using a pattern or a circuit provided for inspection.

  A method for inspecting a microstructure according to the present invention includes a first conductive layer, a second conductive layer, and a sacrificial layer or a space portion provided between the first conductive layer and the second conductive layer. A circuit is formed by connecting the structure and the antenna to the structure. Then, power is supplied to the structure body wirelessly through the antenna, and electromagnetic waves generated from the antenna are detected as characteristics of the structure body.

Another microstructure inspection method according to the present invention includes a first conductive layer, a second conductive layer, and a sacrificial layer or a space portion provided between the first conductive layer and the second conductive layer. A power supply circuit is connected to the structure having
An antenna is connected to the structure body and the power supply circuit to form a circuit.
Then, power is supplied to the structure and the power supply circuit wirelessly through the antenna,
An electromagnetic wave generated from an antenna is detected as a characteristic of the structure.

Another microstructure inspection method according to the present invention includes a first conductive layer, a second conductive layer, and a sacrificial layer or a space portion provided between the first conductive layer and the second conductive layer. A power supply circuit is connected to the structure having
A circuit is formed by connecting the structure and the power supply circuit to the antenna.
And power is supplied to the structure and the electric circuit wirelessly through the antenna,
An electromagnetic wave generated from an antenna is detected as a characteristic of a structure and an electric circuit.

Another microstructure inspection method according to the present invention includes a first conductive layer, a second conductive layer, and a sacrificial layer or a space portion provided between the first conductive layer and the second conductive layer. A control circuit is connected to the structure having
A power circuit is connected to the control circuit,
A circuit having at least an antenna connected to any one of the structure, the control circuit, and the power supply circuit is formed.
And power is supplied to the structure, the control circuit and the power supply circuit wirelessly through the antenna,
An electromagnetic wave generated from an antenna is detected as a characteristic of the structure.

  The control circuit includes a driver or a decoder.

  The power supply circuit includes a booster circuit.

Another microstructure inspection method according to the present invention includes a first conductive layer, a second conductive layer, and a sacrificial layer or a space portion provided between the first conductive layer and the second conductive layer. An antenna is connected to the structure having
The first conductive layer is connected to the first pad;
The second conductive layer is connected to the second pad;
And power is supplied from the pad to the structure,
It is characterized in that a change in electromagnetic waves generated from an antenna is detected as a characteristic of the structure.

Another microstructure inspection method according to the present invention includes a first conductive layer, a second conductive layer, and a sacrificial layer or a space portion provided between the first conductive layer and the second conductive layer. An antenna is connected to the structure having
A first pad is connected to the first conductive layer,
A second pad is connected to the second conductive layer,
Supplying power to the structure wirelessly via an antenna;
A voltage applied to the structure body or a current flowing through the structure body is detected from the first pad and the second pad as a characteristic of the structure body.

Another microstructure inspection method according to the present invention includes a first conductive layer, a second conductive layer, and a sacrificial layer or a space portion provided between the first conductive layer and the second conductive layer. A first structure having a connection to an antenna;
A second structure having the same structure as the first structure is provided adjacent to the first structure;
Supplying power to the first structure wirelessly via an antenna;
An electromagnetic wave generated from the antenna is detected as the characteristic of the first structure, and the characteristic of the second structure is evaluated.

  Another micro structure inspection method according to the present invention is characterized in that the frequency or intensity of electric power is changed, and the intensity of electromagnetic waves generated from an antenna is detected as a characteristic in relation to the change or intensity of the frequency.

Another microstructure inspection method according to the present invention includes a first conductive layer, a second conductive layer, and a sacrificial layer or a space portion provided between the first conductive layer and the second conductive layer. In a structure having
The first conductive layer is connected to the first pad;
The second conductive layer is connected to the second pad;
Supplying power to the structure from the first pad and the second pad;
It is characterized in that a current flowing through the structure is detected as a characteristic of the structure.

Another microstructure inspection method according to the present invention includes a first conductive layer, a second conductive layer, and a sacrificial layer or a space portion provided between the first conductive layer and the second conductive layer. A first structure having a known characteristic is connected to the first antenna;
A second structure having the same structure as the first structure is connected to a second antenna having the same structure as the first antenna;
Supplying power to the first structure wirelessly via the first antenna;
The electromagnetic wave generated from the first antenna is detected and used as the reference characteristic of the second structure,
Supplying power to the second structure wirelessly via the second antenna;
Detecting electromagnetic waves generated from the second antenna as a characteristic of the second structure,
The characteristic of the second structure is evaluated by comparing the characteristic of the detected second structure with the reference characteristic.

  In the microstructure inspection method according to the present invention, for example, the frequency of power is changed, and the intensity of electromagnetic waves generated from the first antenna and the second antenna is detected as a characteristic in relation to the change in frequency. It is characterized by.

  In the microstructure inspection method according to the present invention, the space portion is formed by removing the sacrificial layer. The removal of the sacrificial layer is performed by etching. In this specification, this process is called sacrificial layer etching.

  In the microstructure inspection method according to the present invention, the first structure and the second structure can be provided over the same substrate.

  In the microstructure inspection method according to the present invention, the first structure and the second structure can be provided on different substrates.

  In the other microstructure inspection method according to the present invention, the characteristics include the thickness of the sacrificial layer, the stress applied to the sacrificial layer, and the height of the space (that is, the distance between the first conductive layer and the second conductive layer). ), The spring constant of the structure, the resonance frequency of the structure, the driving voltage of the structure, or the presence or absence of a sacrificial layer. It is also possible to determine the internal stress of the structural layer by combining these measurement results. Note that in the present invention, the first conductive layer and the second conductive layer are preferably provided in parallel.

  It is characterized in that the intensity of electric power is changed and the intensity of electromagnetic waves generated from an antenna is detected as a characteristic in relation to the intensity of electric power.

  It is characterized in that the frequency of electric power is changed, the change in the electromagnetic wave generated from the antenna is detected in relation to the change in the frequency, and the film thickness of the sacrificial layer is evaluated from the frequency at which the intensity of the electromagnetic wave becomes maximum.

  The structure body is formed over a substrate having an insulating surface.

  A micromachine according to the present invention is a micromachine having a microstructure inspected by applying any one of the above-described inspection methods for a microstructure and an electric circuit connected to the microstructure.

  A micromachine according to the present invention includes a first conductive layer formed on a substrate and a second conductive layer provided in parallel with the first conductive layer, and the first conductive layer and the second conductive layer are provided. At least one of the layers is connected to a disconnected wiring.

  The first conductive layer is formed over an insulating substrate.

  The insulating substrate is a glass substrate or a plastic substrate.

  The first conductive layer and the second conductive layer are provided in parallel. In the present specification, the term “parallel” includes a slight deviation and includes a deviation of about ± 5 degrees.

  The micromachine according to the present invention includes a first conductive layer, a second conductive layer provided in parallel with the first conductive layer, and a first conductive layer connected to the same node as the first conductive layer. It has a wiring or a second wiring connected to the same node as the second conductive layer, and the substrate is divided so as to cut the first wiring or the second wiring. In other words, it can be said that the side surface of the substrate and the cut surface of the first wiring or the second wiring are substantially aligned. In this way, the step of removing the wiring can be omitted by leaving the wiring cut.

In the present invention, the micromachine has a space portion inside and has a three-dimensional structure (also referred to as a microstructure), and controls the structure or detects an output from the structure. For having an electric circuit. The structure has two parallel electrodes facing each other across the space portion, one of which is a fixed electrode (first conductive layer in this specification) that is fixed to the substrate and does not move. And the other is a movable electrode (second conductive layer in this specification).
In addition, the movable second conductive layer may be formed as a single layer, but there are cases where a movable layer is configured by laminating an insulating layer or the like on the second conductive layer. Many. In this specification, a movable layer formed by stacking the second conductive layer and the insulating layer is referred to as a structural layer.

In the present invention, by providing an inspection circuit in which an antenna and a structure are connected, a micromachine during and after fabrication can be inspected in a non-contact manner. Thus, the position accuracy at the time of the inspection is not required unlike the inspection in which the prober's needle is brought into contact, and the practitioner can easily perform the inspection. Also, when inspection is performed over a plurality of items and a plurality of substrates, the time required for needle positioning is unnecessary, so that the inspection time can be shortened and productivity can be improved. Furthermore, it is possible to eliminate the risk of destroying a structure having a three-dimensional structure with a space portion due to contact with the needle, and it is possible to eliminate contamination of the substrate due to contact with the needle.

In addition, since the film thickness, operating characteristics, and the like can be inspected in a non-contact manner, the substrate can be returned to the process after the inspection. This eliminates the need to divide or discard the substrate for each inspection, and can improve productivity.

In addition, by detecting changes depending on the power supply and frequency, the state under the opaque layer, for example, the thickness of the sacrificial layer under the structural layer, the progress of sacrificial layer etching, and the height of the space are inspected. can do. Furthermore, since the inspection circuit includes a wireless communication circuit including an antenna, a control circuit, and the like, various structural elements such as an internal stress of the structural layer, a spring constant of the structural layer, a resonance frequency of the structural layer, a driving voltage of the structural body, etc. Dynamic or static characteristics can be inspected.

By applying the inspection method of the present invention, the characteristics of the structure can be inspected during the fabrication of the micromachine, preferably before the sacrifice layer is etched or before the substrate is divided. As a result, the probability of repair when a defect is found increases, and productivity can be improved.

In addition, since a part such as an antenna can be manufactured by the MEMS technology together with the structure forming the inspection circuit, a highly sensitive wireless communication circuit can be formed at the same time, and the inspection accuracy can be improved.

  Embodiments of the present invention will be described below with reference to the drawings. However, the present invention is not limited to the following description. It will be readily understood by those skilled in the art that various changes in form and details can be made without departing from the spirit and scope of the present invention. Therefore, the present invention should not be construed as being limited to the description of the embodiments given below. Note that in describing the structure of the present invention with reference to drawings, the same reference numerals may be used in common in different drawings.

(Embodiment 1)
In this embodiment mode, a micromachine inspection method of the present invention and a circuit provided for performing the inspection will be described. The micromachine inspection method of the present invention is characterized by providing a circuit in which a structure to be inspected, that is, a structure constituting the micromachine, and an antenna are provided, and performing inspection wirelessly using electromagnetic waves. In this specification, the circuit provided for inspection is referred to as an inspection circuit.

FIG. 1A shows an inspection apparatus 101 and an inspection circuit 102. The inspection apparatus 101 communicates with an input / output interface 103 for a measurement person to operate and output measurement results, a control circuit 104 for controlling wireless communication corresponding to measurement items, and an inspection circuit 102. The wireless circuit 105 is provided. The radio circuit 105 has a variable resistor, a variable capacitor, etc., has a variable power source that can change the magnitude and frequency of output power, and an antenna 106, and is controlled by the control circuit 104 as a measurement item. An electromagnetic wave having a corresponding frequency and power is radiated from the antenna 106.

The inspection circuit 102 includes an antenna 108 on a substrate 107 and a structure 109 constituting an inspection element to be inspected, that is, a micromachine. The inspection circuit 102 receives the electromagnetic wave radiated from the inspection device 101, and power is supplied to the structure body 109 by induced electromotive force generated in the antenna 108.

When the frequency, power, or the like of the electromagnetic wave radiated from the antenna 106 of the inspection apparatus 101 is changed, the current flowing in the inspection circuit 102 changes according to the characteristics of the structure 109, and the current change from the antenna 108 of the inspection circuit 102. Electromagnetic waves corresponding to Therefore, the inspection method according to the present invention can inspect the characteristics of the structure 109 in a non-contact manner when the antenna 106 of the inspection apparatus 101 receives the electromagnetic wave.

FIG. 1B shows a part of the inspection device (wireless circuit) and an inspection circuit represented by an electrical equivalent circuit. The inspection apparatus 101 can be represented as a series resonant circuit in which a control circuit 104, a capacitor 110 having a capacitance value C1, a resistor 111 having a resistance value R1, and an antenna 106 having an inductance L1 are connected in series. When a voltage V is applied to the circuit under the control of the control circuit 104, a current i1 flows. Here, when the applied voltage or frequency is changed, the antenna 106 can emit an electromagnetic wave having an intensity proportional to the magnitude of the current flowing in the circuit and a frequency proportional to the time change of the current.

On the other hand, the test circuit 102 can be expressed as a closed circuit in which a resistor 112 having a resistance value R2, an antenna 108 having an inductance L2, and a structure 109 having an impedance Z2 are connected. Further, the antenna 106 of the inspection apparatus and the antenna 108 of the inspection circuit have a mutual inductance M, and the antenna 108 of the inspection circuit that has received the electromagnetic wave radiated from the antenna 106 of the inspection apparatus has a current flowing through the mutual inductance M and the antenna 106. An induced electromotive force u2 proportional to the product of the time change of i1 is generated, and a current i2 flows in the closed circuit.

Here, the self-inductances L1 and L2 and the mutual inductance M are eigenvalues determined by the geometric shape and size of the coil, the medium, and the like. Further, the capacitance value C1 of the capacitor 110 of the inspection apparatus 101, the resistance value R1 of the resistor 111, and the inductance L1 of the antenna 106 are known, and the voltage V applied to the antenna 106 of the inspection apparatus and the flowing current i1 are It is a measurable amount. The current i2 flowing through the inspection circuit 102 reflects the characteristics of the inspection circuit, particularly the structure 109, and the antenna 108 generates an electromagnetic wave proportional to the magnitude of the current i2 and a change with time. Therefore, the impedance Z2 of the structure 109 can be obtained by designing and manufacturing the inductance L2 of the antenna 108 of the inspection circuit 102 and the resistance value R2 of the resistor 112 to have certain values.

The relationship between the electromagnetic wave radiated by the antenna 106 of the inspection apparatus and the electromagnetic wave generated by the antenna 108 of the inspection circuit will be described with reference to FIGS. FIG. 3A shows the relationship between the frequency of the electromagnetic wave radiated from the inspection device and the intensity of the electromagnetic wave generated by the antenna of the inspection circuit (the horizontal axis indicates the frequency and the vertical axis indicates the intensity). For example, when the structure 109 has a capacitive impedance, the inspection circuit is a resonance circuit in which a resistor, an inductance, and a capacitor are connected. Therefore, as shown in FIG. 3A, an electromagnetic wave having an intensity peak at a specific frequency f determined by a resistance value, an inductance, and a capacitance value is output. As described above, by changing the frequency of the electromagnetic wave radiated from the inspection apparatus 101, it is possible to obtain the inspection circuit characteristic 113 depending on the frequency. For example, when the antenna 106 is manufactured so that the inductance L is L = 10 μH and the structure 109 is manufactured so that the capacitive impedance of the structure is about 500 pF, the resonance frequency f ₀ is f ₀ = 2. Obtained at 25 GHz.

FIG. 3B shows the relationship between the intensity of the electromagnetic wave radiated by the antenna 106 of the inspection apparatus 101 and the intensity of the electromagnetic wave generated by the antenna 108 of the inspection circuit 102 (the horizontal axis is from the inspection apparatus). The intensity of the electromagnetic wave, and the vertical axis indicates the intensity of the electromagnetic wave from the inspection circuit). For example, when the structure 109 has a resistive impedance, the inspection circuit is a resonance circuit in which a resistor and an inductor are connected. Here, when an electromagnetic wave whose intensity is changed at a specific frequency is radiated from the inspection apparatus 101, the magnitude of the current flowing through the inspection circuit changes. Therefore, as shown in FIG. 3B, the inspection circuit outputs an electromagnetic wave having an intensity proportional to the current value. As described above, when the power of the electromagnetic wave radiated from the inspection apparatus is changed, the voltage generated in the inspection circuit and the flowing current are changed, so that the characteristic 114 of the inspection circuit can be obtained.

Here, by designing and producing the inductance L2 of the antenna 108 of the inspection circuit 102 and the resistance value R2 of the resistor 112 to have a certain value, the characteristic of the inspection circuit reflects the characteristic of the structure. Become. Therefore, by producing an inspection circuit according to the measurement item and supplying electric power according to the purpose, the thickness of the sacrificial layer formed during the production of the structure, the height of the space portion of the structure, the structure The characteristics of the structure such as the film stress of the layer, the spring constant of the structure layer, the resonance frequency of the structure layer, the driving voltage of the structure, etc. can be inspected in a non-contact manner.

In addition, parameters related to the characteristics of the structure are extracted by various operations from the measurement results obtained by the above-described measurement, and whether or not the parameters are within the range defined by the specifications. Evaluation of properties can be performed.

In addition, the inspection of the characteristics of the structure using the above-described inspection circuit is not performed by obtaining the characteristics of the structure itself from the measurement results, but by comparing them with the measurement results of the reference structure with known characteristics. Is also possible. That is, an inspection circuit having a structure whose characteristics such as film thickness and driving voltage are known is measured by the above method. After that, an inspection circuit having a structure with an unknown characteristic is measured under the same conditions, and the result is compared with the measurement result of the structure having the known characteristic to evaluate the characteristic of the unknown structure. It can be carried out.

An example of the inspection method will be described with reference to FIG. Here, as an example, the case where the structure 109 has capacitive impedance and the characteristics of the structure to be inspected are reflected in the capacitance value will be described. First, an inspection circuit having a structure whose characteristics to be inspected are known is inspected. Since the impedance of the structure is capacitive and the inspection circuit is a series resonant circuit, the inspection supplies power with a constant intensity and a changed frequency from the inspection device, and receives output from the inspection circuit. As shown in FIG. 4, the result is a frequency at which the horizontal axis represents the frequency of the electromagnetic wave emitted by the inspection apparatus and the vertical axis represents the intensity of the electromagnetic wave output from the inspection circuit, and the intensity takes a maximum value at a specific frequency f. The result of characteristic 115 can be obtained. This is the measurement result of the reference frequency characteristic 115.

Further, based on the measurement result of the frequency characteristic 115, an allowable range that can be taken by the result of measuring a structure whose characteristic to be inspected is unknown may be set. For example, as shown by a dotted line in FIG. 4, a predetermined range can be set in the positive and negative directions from the resonance frequency f obtained by the above measurement, and this can be set as an allowable range of the resonance frequency. In addition, it is possible to set allowable ranges such as output intensity and resonance Q value. This allowable range is preferably selected from the range of operation specifications by selecting an optimum range for evaluating the characteristics of the structure to be inspected.

Next, an inspection circuit having a structure whose characteristics to be inspected are unknown is measured under the same conditions. For example, when the measurement result is similar to the measurement result of the reference frequency characteristic 115, such as the frequency characteristic 116 indicated by a two-dot chain line in FIG. 4, this structure is a structure that has been measured before. Can be evaluated as having the same characteristics. It is also possible to evaluate that this structure has the same characteristics as the previously measured structure if the predetermined variable is within the tolerance set above.

Further, when the measurement result is significantly different from the reference measurement result as shown by the one-dot chain line in FIG. 4 and the intensity has a maximum value outside the allowable range set above, this structure is used. It can be appreciated that the body has properties that are significantly different from the previously measured structure. In addition, even if the maximum value is within the allowable range as in the frequency characteristic 118 indicated by the one-dot chain line in FIG. 4, if the curve has two or more maximums, it is determined that the characteristic is different. be able to.

In this way, it is possible to evaluate a structure having an unknown characteristic by inspecting a structure having a known characteristic and a structure having an unknown characteristic using an inspection circuit under the same conditions, and comparing the results. it can. Here, when the quality of a structure is evaluated as good or bad, a structure having a characteristic that is determined to be a non-defective product is used as a structure that has a known characteristic and serves as a reference for evaluation. And it is desirable to evaluate good or bad compared with the result of the standard that the good product can take.
Such an inspection method based on the comparison of results can be effectively applied when it is difficult to directly determine the characteristics of the structure from the electromagnetic waves output from the inspection circuit.

As described above, by applying the present invention, the characteristics of the structure body during and after fabrication can be inspected in a non-contact manner. Thus, the position accuracy at the time of the inspection is not required unlike the inspection in which the prober's needle is brought into contact, and the practitioner can easily perform the inspection.
Also, when inspection is performed over a plurality of items and a plurality of substrates, the time required for needle positioning is unnecessary, so that the inspection time can be shortened and productivity can be improved. Furthermore, the danger of destroying the structure which has a three-dimensional structure with a space part by contact of a needle | hook can be eliminated.

In addition, since the film thickness, operating characteristics, and the like can be inspected in a non-contact manner, the substrate can be returned to the process after the inspection. This eliminates the need to divide or discard the substrate for each inspection, and can improve productivity.

Further, by detecting changes depending on the intensity and frequency of the supplied power, various dynamic characteristics and / or static characteristics of the structure can be inspected.

By applying the inspection method of the present invention, the characteristics of the structure can be inspected during the fabrication of the micromachine, preferably before the sacrifice layer etching or before the substrate is cut. As a result, the probability of repair when a defect is found increases, and productivity can be improved.

Furthermore, by comparing with the measurement results of the reference structure, it is possible to simply determine whether the structure is good or bad by inspection, and when there is no need to obtain individual values, or from the electromagnetic wave output by the inspection circuit, It can be effectively applied when it is difficult to directly obtain characteristics.

(Embodiment 2)
In this embodiment, an example of a method for measuring the film thickness in a non-contact manner by applying the inspection method described in the above embodiment will be described.

In surface micromachining, a sacrificial layer is first formed on a substrate, and a structural layer is formed thereon. After that, by removing the sacrificial layer, a structure in which part of the structure layer is supported away from the substrate and a micromachine having the structure are manufactured. Here, a layer that becomes a movable part of the structure is referred to as a structural layer in this specification.
In addition, in order to form a space which is a region for moving the structural layer, a layer to be removed later by etching is referred to as a sacrificial layer. The etching is called sacrificial layer etching.
The sacrificial layer is a very important layer for forming the space portion where it is desired to be a space portion, and removing the structure layer from the substrate by removing the structure by etching the sacrificial layer.
However, since the sacrificial layer is removed, structures and micromachines that are in the form of final products often do not have a sacrificial layer.

As described above, the thickness of the sacrificial layer and the height of the space formed by removing the sacrificial layer (the distance from the substrate to the structural layer) affect the operation characteristics of the structure. Control and measurement become very important.

In this embodiment mode, a method for inspecting the thickness of the sacrificial layer and the height of the space formed after removing the sacrificial layer in a non-contact manner will be described.

The inspection uses the inspection circuit described in the above embodiment. 5A to 5C are cross-sectional views of a structure body included in the inspection circuit, and FIG. Note that FIG. 5D is a top view before the sacrifice layer is etched, and a cross-sectional view taken along a dotted line A-A ′ corresponds to FIG. The structure can be manufactured by applying a process for manufacturing a general semiconductor element. First, as shown in FIG. 5A, a first conductive layer 202 is formed over a substrate 201, a sacrificial layer 203 is formed thereon, and a second conductive layer 204 is formed thereon. Produced. Here, a silicon substrate is generally used as the substrate 201, but a glass substrate, a plastic substrate, a metal substrate, or the like may be used. When a metal substrate or the like is used, it is desirable to perform a surface treatment such as forming an insulating film. In addition, for example, by forming a structure on a plastic substrate, a lightweight and flexible thin micromachine can be formed. A thin micromachine can also be formed by polishing and thinning a silicon substrate, a glass substrate, and a metal substrate.

Further, the first conductive layer 202 and the second conductive layer 204 are formed using a conductive material, and the sacrificial layer 203 is formed using an insulating material whose relative dielectric constant is given by ε. The film thicknesses of the first conductive layer 202 and the second conductive layer 204 are, for example, not less than 100 nm and not more than 700 nm (for example, 400 nm).

In addition, as illustrated in FIG. 5B, the structure body can be formed by forming a second conductive layer 204 and an insulating layer 205 over the sacrificial layer 203 and then processing the film. . Thereafter, as shown in FIG. 5C, the sacrificial layer 203 is removed by etching to form a space portion 206, whereby a final structure can be formed.

Here, an example of materials used for the first conductive layer 202, the second conductive layer 204, the sacrificial layer 203, and the insulating layer 205 is described.
The first conductive layer 202 and the second conductive layer 204 are formed using a conductive material, for example, a metal such as aluminum, tungsten, tantalum, titanium, gold, or rubidium and a nitride or oxide thereof, or the above metal. It is formed by a sputtering method using an alloy having a main component.
In the case where hydrofluoric acid is used as an etchant in the sacrifice layer etching, the sacrifice layer 203 is formed using phosphorous glass (PSG) or silicon oxide, and the insulating layer 205 is formed using silicon having a polycrystalline structure. be able to. In the case of using ammonia perwater as an etchant, the sacrificial layer 203 can be formed using tungsten (W) and the insulating layer 205 can be formed using silicon oxide.

  Note that wet etching or dry etching can be applied to the removal of the sacrificial layer 203. By removing the sacrificial layer 203, a space portion 206 is formed.

In this specification, both the structure before the sacrificial layer etching and the structure after the sacrificial layer etching are described as a “structure”. However, the structure for forming the micromachine is subjected to the sacrificial layer etching. Since it is a structure having a space portion, it is described as a final structure here.
Further, the structure in FIG. 5C shows a structure obtained by applying sacrificial layer etching to the structure in FIG. 5B.

The process for producing the above structure shows the simplest example. Therefore, for example, the first conductive layer can be formed on the substrate after forming a protective layer serving as a base. By forming the protective layer over the substrate, contamination from the substrate to the structure can be prevented, and internal stress of other layers formed over the substrate can be reduced. As the protective layer, silicon oxide, silicon nitride, silicon nitride containing oxygen (also referred to as silicon nitride oxide), silicon oxide containing nitrogen (also referred to as silicon oxynitride), or the like can be used. Note that the protective layer may have a stacked structure using the above-described materials. As the protective layer, for example, silicon oxide containing nitrogen with a thickness of 50 nm to 200 nm (preferably 100 nm to 150 nm) can be formed by a plasma CVD method.

It is also possible to form the sacrificial layer 203 after forming a protective layer on the first conductive layer 202. Further, a protective layer can be formed above and below the second conductive layer 204, and each layer such as a conductive layer and an insulating layer can be formed not only as a single layer but also as a stacked layer. By forming a protective layer over the first conductive layer 202 and under the second conductive layer 204, deterioration of the surface of the conductive layer during sacrificial layer etching can be prevented. Further, by forming the structural layer by stacking the second conductive layer and the protective layer, the internal stress of the structural layer can be relaxed and the hardness of the structural layer can be arbitrarily controlled.

In order to operate the structure, a fixed electrode (first conductive layer) that is fixed to the substrate 201 and does not move, a sacrificial layer, and a movable electrode (second conductive layer) that moves as a structure layer are sequentially stacked. In many cases, the present invention measures the thickness of the sacrificial layer using this structure. Here, “fixed electrode” and “movable electrode” are for expressing whether the electrode is mechanically movable or fixed to a substrate or the like, and the potential applied to the electrode is fixed. Such meanings are not included.

5D, the first conductive layer 202, the sacrificial layer 203, and the second conductive layer 204 are formed to overlap with each other, so that the first conductive layer 202 and the second conductive layer It is assumed that a portion 207 area S overlapping with the layer 204 is already known at the time of design.

The structure body formed as described above can be regarded as a parallel plate type capacitor in which the first conductive layer and the second conductive layer face each other and an insulator is provided therebetween. Therefore, the inspection circuit in which the antenna and the structure are connected in a closed circuit is a resonance circuit in which the inductor and the capacitor are connected via a resistor. Here, the resistance is a parasitic resistance generated by wiring connecting the antenna and the structure.

The antenna is manufactured so as to have an inductance L that resonates at a certain frequency with the capacitance value of the structure that is expected at the time of design. The resistance value R of the parasitic resistance can be obtained from the resistivity specific to the wiring material and the cross-sectional area and length of the wiring.

When electromagnetic waves are radiated from the inspection device to the inspection circuit thus manufactured, an induced electromotive voltage V is generated at both ends of the antenna. Here, when the frequency of the electromagnetic wave is changed, the largest absorption occurs at the frequency f0 at which the test circuit including the antenna, the resistor, and the capacitor (structure) resonates, and the current i flowing in the test circuit becomes the maximum.

FIG. 6 shows the frequency characteristics of the current i flowing in the inspection circuit described above. Since the test circuit is a resonant circuit of an inductor, a capacitor, and a resistor, the current i is indicated by a curve having a peak around a certain frequency. The frequency characteristic 208 of the current before the sacrifice layer etching has a peak current value around the frequency f0 as shown in FIG.

Since the antenna of the inspection circuit generates an electromagnetic wave proportional to the time change of the current i flowing in the inspection circuit, the frequency characteristic of the current flowing in the inspection circuit can be obtained by receiving this electromagnetic wave with the inspection device. .

Here, the resonance frequency f ₀ of the inspection circuit can be expressed by Expression (1). Further, the capacitance C of the structure can be expressed by Expression (2).

Thus, the resonance frequency f ₀ of the inspection circuit is determined by the inductance L, the resistance R, and the capacitance C of the structure. The inductance L, the resistance R, the overlapping area S of the two conductive layers, and the relative dielectric constant ε of the sacrificial layer are known at the time of design and production. Therefore, the thickness of the sacrificial layer can be obtained from the resonance frequency f ₀ of the inspection circuit. This method can be applied to both structures shown in FIGS.

Next, even after the sacrificial layer is removed by sacrificial layer etching, the resonance frequency can be measured in the same manner. When the resonance frequency at this time is f1, the height of the space, that is, the distance between the two conductive layers can be obtained by measuring the frequency f1 from the equations (1) and (2).

FIG. 6 shows the frequency characteristic 209 of the current i of the inspection circuit after the sacrificial layer etching. The frequency characteristic 209 of the current after the sacrificial layer etching has a peak current value around the frequency f1, as shown in the figure. After the sacrifice layer etching, the relative permittivity of the space can be approximated to 1. Therefore, when the distance between the two conductive layers before and after the sacrifice layer etching is equal, the resonance frequency of the inspection circuit is expressed by the following equation (3). be able to.

However, if the thickness of the sacrificial layer is d before the sacrificial layer etching, but the distance between the two conductive layers changes to d ± Δd after the sacrificial layer etching, the resonance frequency is expressed by the equation (4). (The resonance frequency at this time is assumed to be f2).

Therefore, as shown in FIG. 6, the frequency characteristic 210 of the current flowing through the inspection circuit has a peak at f2 where the frequency is shifted from f1 to the minus side or the plus side.

By applying the present invention as described above, it is possible to inspect the thickness of the sacrificial layer and inspect the height of the space using the same inspection circuit before and after etching the sacrificial layer. And the characteristic of a structure can be evaluated for every process by comparing those test results. In addition, the same structure is inspected before and after etching the sacrificial layer. For example, if the thickness of the sacrificial layer and the height of the space are different by comparing the results, the strain of the structural layer can be detected. It is possible to evaluate characteristics such as internal stress and spring constant of the structural layer.

Here, in the case where the sacrificial layer is formed of a conductive material, the structure before the sacrificial layer etching cannot be regarded as a capacitor, and thus the above method cannot be used. However, if this structure is regarded as a resistance element, the inspection circuit becomes a resonance circuit in which an inductor and a resistor are connected. Therefore, the film thickness can be measured in a non-contact manner using a method different from the above. Here, since the resistance value of the structure reflects the film thickness of the sacrificial layer, the film thickness can be inspected by obtaining the current-voltage characteristics of the structure.

As in the above case, the overlapping area S of the two conductive layers forming the structure and the resistivity ρ of the sacrificial layer are known at the time of design and fabrication. The inspection apparatus radiates electromagnetic waves having a constant frequency and varying output intensity with respect to this inspection circuit. The resistance value of the structure can be obtained from the response of the inspection circuit corresponding to the change in the output intensity, and the film thickness of the sacrificial layer can be obtained. Here, in order to increase the inspection accuracy, it is desirable that the frequency of the electromagnetic wave emitted by the inspection apparatus is the resonance frequency of the inspection circuit.

Further, the characteristic evaluation of the structure using the inspection circuit can be performed by comparing with the measurement result using the reference structure as described in the above embodiment. For example, a structure having a known film thickness is measured under certain conditions. Thereafter, the structure to be inspected can be measured under the same conditions, and the result can be evaluated by comparing the result with the measurement result of the known structure.

The surface micromachine is manufactured by forming and processing a thin film on a substrate, but an internal stress is generated by forming the thin film on a different material. By performing sacrificial layer etching, an adjacent film (sacrificial layer) is removed from the thin film forming the structure and the internal stress is released, so that the portion not in contact with the substrate is deformed into a concave or convex shape. When the film forming the structure is deformed in this manner, the height of the space changes, so that the characteristics of the structure change greatly. Therefore, the characteristics of the structure can be estimated by measuring the height of the space, and whether the structure is good or bad can be determined.

By measuring the structure without contact as in the present invention, the structure can be easily evaluated without destroying the structure. Furthermore, by inspecting the characteristics of the structure based on the intensity and frequency characteristics of electromagnetic waves, it is possible to inspect even those that are not visible with a microscope, such as the thickness of the film below the metal film. When measuring the film thickness under such an opaque film, the film thickness is generally measured by dividing the substrate and observing the cross section, but easily measured by applying the present invention. And the substrate can be returned to the process after inspection. This does not need to be discarded and can improve productivity.

By applying the present invention as described above, the thickness of the sacrificial layer and the height of the space can be inspected using the same inspection circuit before and after the sacrificial layer etching. Properties can be evaluated on a process-by-process basis. This is because by performing a process inspection before sacrificial layer etching or dicing, the probability of repairing when a defect is found increases, and productivity can be improved. Further, the characteristics (stress etc.) of the layer forming the structural layer can be evaluated by inspecting the same structure before and after the sacrifice layer etching and comparing the results.

  Note that this embodiment mode can be freely combined with the above embodiment modes.

(Embodiment 3)
In this embodiment, with respect to the inspection method described in the above embodiment, a structure of a different inspection circuit and an example of an inspection method using the circuit will be described. The inspection method of the present invention can also be applied to the inspection circuits shown in FIGS.

The inspection circuit illustrated in FIGS. 7A and 7B includes an antenna 301, a structure 302, and a measurement pad 303. The wiring resistance of the inspection circuit is indicated by a resistor 304. FIG. 7C includes a structure 302 and a measurement pad 303. In this inspection circuit, the antenna and the structure are connected so as to be a closed circuit, and a pad is connected to the same node as the conductive layer constituting the structure. The place where the pad is connected and the number thereof can be determined depending on the object to be measured.

When this inspection circuit is used, the characteristics of the structure can be inspected by supplying electric power by bringing the probe needle into contact with the pad and receiving electromagnetic waves generated from the antenna. On the contrary, it is also possible to supply electric power wirelessly from the inspection device to the inspection circuit via the antenna 301 and measure the current flowing through the structure or the applied voltage by bringing the probe needle into contact with the pad.

Here, an example of a method for measuring the thickness of the sacrificial layer by applying the latter method will be described. 7A to 7C has the structure shown in FIG. 5B and is connected to the same node as the first conductive layer and the same node as the second conductive layer of the structure. 2 pads. When electromagnetic waves are radiated from the inspection device to the inspection circuit, an induced electromotive voltage is generated in the antenna 301. Here, when the frequency of the electromagnetic wave is changed, the largest absorption occurs at the resonance frequency of the inspection circuit, and the induced electromotive voltage generated is maximized. Here, the resonance frequency of the inspection circuit can be obtained by bringing a probe needle into contact with the pad and measuring the frequency characteristics of the voltage applied to the structure. As described in the second embodiment, the thickness of the sacrificial layer can be evaluated from this resonance frequency.

Further, by performing the above measurement before and after etching the sacrificial layer, the thickness of the sacrificial layer and the height of the space of the structure (distance between two conductive layers) are compared, and the characteristics (stress of the layer forming the structural layer) Etc.) can be evaluated. Here, the space included in the structure body is formed by removing the sacrificial layer between the first conductive layer and the second conductive layer as described in the above embodiment.

In addition, when an inspection is performed by applying an AC voltage and a reference voltage (for example, a ground voltage or a constant voltage) to the inspection circuit, the inspection circuit shown in FIG. 7B can be applied. . The inspection circuit in FIG. 7B includes an antenna, a structure body, and one pad connected to part of the structure body. For example, a certain voltage can be supplied to the first electrode of the structure via a pad, and power can be supplied via an antenna. Since the mechanical resonance frequency of the structure can be known by performing such an operation, characteristics such as whether the sacrificial layer has been completely removed by sacrificial layer etching, the film stress of the structural layer, or the spring constant can be obtained. . This is because the above characteristics depend on the mechanical resonance frequency of the structure.

Further, the inspection of the thickness of the sacrificial layer and the inspection of whether or not the sacrificial layer has been removed can be performed by a contact type inspection using an inspection circuit shown in FIG. The inspection circuit in FIG. 7C includes a structure, a pad connected to the same node as the first conductive layer of the structure, and a pad connected to the same node as the second conductive layer of the structure. The And it can test | inspect by supplying alternating current electric power from a pad with respect to the above inspection circuits, and measuring the frequency dependence and intensity dependence.

  As described above, by applying the inspection method to the structure shown in FIGS. 5A to 5D, the substrate is broken without breaking the substrate and performing SEM (Scanning Electron Microscope) observation. It is possible to perform inspection for process confirmation. In addition, since the substrate after this inspection can be returned to the process, productivity can be improved.

In addition, the characteristic evaluation of the structure using the inspection circuit illustrated in FIGS. 5A to 5D is compared with the measurement result using the reference structure as described in the above embodiment. It is also possible to do this. For example, when it is difficult to determine the film thickness from the frequency dependence of the voltage, a structure having a known film thickness is measured by the above method. Thereafter, the structure to be inspected is measured under the same conditions, and the result can be evaluated by comparing the result with the measurement result of the known structure.

In this way, by inspecting the characteristics of the structure by the intensity and frequency characteristics of electromagnetic waves, it is possible to inspect even those that are not easily seen with a microscope, such as the thickness of the film provided under the metal film. it can. Further, by inspecting the process before sacrificial layer etching or dicing, the probability of repairing when a defect is found is increased, and productivity can be improved.

  Note that this embodiment mode can be freely combined with the above embodiment modes.

(Embodiment 4)
In this embodiment, a micromachine inspection method performed using an inspection circuit including a power supply circuit will be described. The power supply circuit has a function of generating a constant voltage from an AC voltage and can supply constant voltage power to the structure. Therefore, the inspection circuit has a power supply circuit to measure the characteristics of various structures. Can do.

8A to 8C show examples of configurations that the inspection circuit can take. The inspection circuit in FIG. 8A includes an antenna 401, a capacitor 402, a structure body 403, a power supply circuit 404, and a switching element 405. Here, the switching element is a three-terminal element having an input terminal such as a transistor, an output terminal, and a control electrode, for example, and controls whether the input terminal and the output terminal are connected (ON or OFF) by the control electrode. It is an element that can be used. Note that a thin film transistor can be used as the switching element. As the thin film transistor, either a top gate type or a bottom gate type may be used.

Although the structure 403 can have various structures depending on its shape, it is assumed here that the structure 403 includes two input terminals 420 and 421 and one output terminal 422 as an example. Further, the power supply circuit 404 has one input terminal 409 and two output terminals 410 and 411.
The inspection circuit is connected so that the antenna 401, the capacitor 402, and the switching element 405 are closed circuits. The capacitor 402 and the switching element 405 are both connected to the input terminal 409 of the power supply circuit 404, and the control electrode (switching) of the switching element 405 is switched. The output terminal 422 of the structure 403 is connected to a gate electrode in the case where the element is a transistor.

In this inspection circuit, the antenna 401 and the capacitor 402 absorb electromagnetic waves radiated from the inspection device at a specific resonance frequency, and generate a large induced electromotive force. The induced electromotive force is supplied to the input terminal 409 of the power supply circuit 404, and the power supply circuit rectifies the power to generate a constant voltage serving as a reference and a constant voltage higher than the reference voltage. Here, the reference voltage is a reference voltage in the inspection circuit and is generally called a ground voltage, a ground, or the like, but is referred to as a reference voltage in this specification. The power supply circuit generates a constant voltage higher than the reference voltage, and this voltage is referred to as a power supply voltage in this specification. That is, the power supply circuit generates a power supply voltage and a reference voltage, outputs the power supply voltage from the output terminal 410 and the reference voltage from the output terminal 411, and supplies these voltages to the entire inspection circuit including the structure 403.

The structure 403 operates with the power supplied from the power supply circuit 404 and outputs an output (voltage change) corresponding to the operation characteristics to the switching element 405. When the switching element 405 is turned on and off by the output of the structure 403, the impedance associated with the antenna 401 and the capacitor 402 changes, and the antenna outputs an electromagnetic wave reflecting the operating characteristics of the structure. The characteristics of the structure body 403 can be evaluated by receiving the electromagnetic wave output from the antenna by the inspection device.

In addition, as illustrated in FIG. 8B, the inspection circuit can include an antenna 401, a capacitor 402, a power supply circuit 404, and a structure body 403. That is, the inspection circuit does not have a switching element, and the input terminal 409 of the power supply circuit is connected to the antenna 401 via the capacitor 402. Similarly to the above, the power supply circuit 404 generates a power supply voltage and a reference voltage, outputs the power supply voltage from the output terminal 410, and outputs the reference voltage from the output terminal 411 to supply the structure 403. The output terminal 411 of the power supply circuit 404 is connected to one end of the antenna to which the capacitor 402 is not connected.

The inspection circuit illustrated in FIG. 8A is configured to output an electromagnetic wave according to the operating characteristics of the structure when the switching element is turned on and off, and thus can be applied when the output from the structure is digital. For example, the structure has a switch function, and can be used when the ON / OFF characteristics of the structure are inspected. On the other hand, in the inspection circuit illustrated in FIG. 8B, the antenna 401 is directly connected to the output terminal of the structure body 403. The inspection circuit illustrated in FIG. 8B can output an electromagnetic wave in accordance with a change in voltage of the output terminal of the structure. Therefore, this inspection circuit can be applied when the output from the structure is analog, for example, when the structure has a variable capacitance and the capacitance change is inspected.

Further, the inspection circuit can include an antenna 401, a capacitor 402, a switching element 405, a power supply circuit 404, a control circuit 406, and a structure 403 as illustrated in FIG.
The antenna 401, the capacitor 402, and the switching element 405 are connected to form a closed circuit, and the power supply circuit 404 and the control circuit 406 are connected to one end of the antenna 401 through the capacitor 402. The power supply circuit rectifies the AC voltage as described above, and the rectified power is supplied to the control circuit and the structure. The ground potential generated by the power supply circuit is connected to the other end of the antenna.

The control circuit 406 has a function of controlling the structure 403 by extracting a control signal transmitted from the inspection apparatus from the electromagnetic wave received by the antenna 401. The structure controlled by the control circuit 406 outputs its operating characteristics to the control electrode of the switching element. Since the switching element is turned on and off in accordance with the output of the structure, the impedance associated with the antenna and the capacitance changes. Therefore, the antenna outputs an electromagnetic wave reflecting the output of the structure.

In the inspection circuit in FIG. 8C, the terminal of the structure body may be connected to one end of the antenna without the switching element.

  Next, the power supply circuit 404 constituting the inspection circuit will be described with reference to FIGS. As shown in FIG. 9A, the power supply circuit 404 includes a diode 407 and a capacitor 408, and rectifies the AC voltage input from the input terminal 409 connected to the antenna into a constant voltage. The rectified power supply voltage is output from the output terminal 410 to each part in the inspection circuit. The power supply circuit 404 generates a reference voltage simultaneously with the power supply voltage, outputs it from the output terminal 411, and supplies it to the antenna and the structural layer.

The power circuit 404 shown here connects two diodes 407, one to rectify the voltage by connecting it in the forward direction and the other to connect it in the reverse direction to prevent backflow. However, it is also possible to configure a power supply circuit by performing rectification and prevention of backflow using two or more diodes. Further, although the power supply circuit 404 includes the diode 407 and the capacitor 408, it can also be configured using a passive element such as an inductor.

In addition, as illustrated in FIG. 9B, the power supply circuit 404 can be formed using a rectifier circuit 412 and a regulator 413. The rectifier circuit 412 rectifies the AC voltage supplied from the input terminal 409 connected to the antenna, similarly to the power supply circuit 404, and the regulator holds the voltage generated by the rectifier circuit 412 at a certain voltage. Therefore, the power supply circuit 404 outputs the voltage held at a constant value by the regulator 413 and the reference voltage to each part in the inspection circuit from the output terminals 410 and 411.

When the power of the electromagnetic wave radiated from the inspection apparatus is large, the rectifier circuit may generate a high voltage and supply it to the structure, which may destroy the structure. In such a case, a predetermined power supply voltage can be supplied to the structure body by providing a regulator in the power supply circuit.

On the other hand, when a high voltage is to be supplied to the structure body, the power supply circuit can include a booster circuit. The booster circuit can be configured using a diode and a capacitor. When the power supply circuit includes a booster circuit, a high voltage that cannot be generated by the power supply circuit or a negative voltage can be generated and supplied to the structure.

As described above, the power supply voltage can be supplied to the structure body by providing the power supply circuit as described above in the inspection circuit, so that the static characteristics of the structure body can be measured wirelessly. In addition, since the inspection circuit has a power supply circuit, the sacrificial layer thickness, space height, structural layer film stress, structural layer spring constant, structural layer resonance frequency, structural drive voltage, etc. Body characteristics can be measured.

Next, a method for measuring the driving voltage of the structure body using the inspection circuit illustrated in FIG. As shown in the figure, the inspection circuit includes an antenna 401, a capacitor 402, a structure 403, a power supply circuit 404, and a switching element 405. The power supply circuit 404 includes a rectifier circuit 412 and a booster circuit 414.

As shown in FIG. 10B, the structure of the inspection circuit includes a first conductive layer 415, an output terminal 416, and a structure layer 417 on a substrate. The structural layer 417 includes a second conductive layer 418 that faces the first conductive layer 415. A part of the structural layer 417 is supported by the substrate, and the other part faces the substrate through a space.
When a voltage is applied between the first conductive layer 415 and the second conductive layer 418 of the structure body 403, the structure layer 417 moves and is attracted to the substrate. When the applied voltage is further increased, the structural layer 417 is drawn to the substrate and the first conductive layer 415 and the second conductive layer 418 are in contact with each other. This voltage is called a pull-down voltage. Here, a pull-down voltage inspection method will be described as an example of a structure driving voltage.

The power supply circuit 404 has an input terminal connected to one end of the antenna via the capacitor 402, generates a power supply voltage from an AC induced electromotive voltage generated in the antenna by the rectifier circuit 412, and generates a high voltage by the booster circuit 414. Supply to the second conductive layer of the structure. The reference voltage generated by the power supply circuit is supplied to one end of the antenna and the first conductive layer of the structure body. Here, as the power supplied to the inspection circuit by the inspection device increases, the power supply voltage generated by the rectifier circuit increases, so that the booster circuit that generates a high voltage based on the power supply voltage is proportional to the power supply voltage. Outputs a large voltage.

In addition, the output terminal provided in the same layer as the first conductive layer of the structure body is connected to the control electrode of the switching element and is not electrically connected to the first conductive layer. When a reference voltage is supplied to the first conductive layer of such a structure and a high voltage generated by the power supply circuit is supplied to the second conductive layer, the structure layer moves as described above, and the second conductive layer Is in contact with the first conductive layer and the output terminal. When the output terminal is in contact with the second conductive layer, the operation of the switching element is changed, and the impedance associated with the antenna and the capacitor is changed.

Here, when the curve 419 is drawn with the horizontal axis representing the intensity of the electromagnetic wave emitted by the inspection device and the vertical axis representing the intensity of the electromagnetic wave output from the inspection circuit, the horizontal axis is shown in FIG. It can be seen that at point X, the intensity of the electromagnetic wave output from the inspection circuit changes. This point indicates a pull-down voltage.

It is also possible to evaluate the characteristics of the structural layers constituting the structure by inspecting the height of the space of the structure by the method described in the above embodiment and further inspecting the pull-down voltage in this way. . For example, the pull-down voltage is determined in relation to the height of the space and the shape and stress of the structural layer. Therefore, the stress of the layer forming the structural layer can be evaluated by performing these inspections.

Further, a method for inspecting whether the sacrificial layer has been completely removed by the sacrificial layer etching or whether the sacrificial layer remains due to insufficient sacrificial layer etching, using the inspection circuit having the power supply circuit as described above. Will be described with reference to FIGS. 2A shows a cantilever structure, and FIG. 2B shows a bridge structure formed in a bridge shape.

For example, as shown in FIG. 2A, in the inspection of a structure having a cantilever structure, a constant voltage is applied to the first conductive layer 202 and a high-frequency voltage is applied to the second conductive layer 204. Supply. This can be performed, for example, using the inspection circuit described in Embodiment 3 with reference to FIG.
If the length of the beam is known at the time of design and fabrication, the beam will resonate at the resonance frequency of the structure. However, if there is a remaining sacrificial layer 211 (a sacrificial layer that has not been removed by the sacrificial layer etching), the length of the beam changes, and resonance does not occur at the frequency (in detail, the sacrificial layer remaining 211 substantially As the length of the beam becomes shorter, the resonance frequency shifts higher.) By measuring this resonance frequency, it can be inspected whether or not the sacrificial layer remains.

Further, as described above, it is possible to inspect whether or not there is a sacrificial layer remaining by measuring the pull-down voltage. This utilizes the fact that the pull-down voltage is determined by the structure of the structure. That is, in the case of a cantilever beam, the pull-down voltage increases as the length of the beam becomes shorter. Therefore, it is possible to inspect whether there is a sacrificial layer remaining by measuring the voltage change.

In addition, when the remaining sacrificial layer 211 is very large, or when the sacrificial layer remaining 211 exists in the beam structure as shown in FIG. 2B, pull-down does not occur, so that the inspection can be performed.

Furthermore, even if the structure is a cantilever beam (FIG. 2A) or a beam structure (FIG. 2B), the impedance of the structure changes as in the inspection method described in the second embodiment. The above-mentioned inspection can be performed by using. For example, when the structure has a capacitive impedance (that is, when the sacrificial layer is an insulating material having a dielectric constant ε), if the remaining sacrificial layer exists, the capacitance of the structure has a dielectric constant ε0 between the conductive layers. The capacitance value is a capacitance value (dielectric constant of vacuum) and a capacitance value having a dielectric constant ε connected in parallel. By utilizing this change in capacitance, it is also possible to inspect whether there is a sacrificial layer remaining. When the structure has a resistive impedance (that is, when the sacrificial layer is a conductive material), the structural layer does not have conductivity if the sacrificial layer is completely removed. However, since the structure shows conductivity when the sacrificial layer remains, it can be inspected.

  Therefore, it is possible to easily inspect whether or not the sacrificial layer is completely removed by applying the above inspection method using an easy means such as an optical microscope. It is also possible to return the inspected substrate to the process. Therefore, productivity can be improved.

As described above, by providing the power supply circuit and the control circuit in the inspection circuit, various static characteristics or dynamic characteristics of the structure, for example, the thickness of the sacrificial layer, the height of the space, and whether the sacrificial layer is removed. In addition, the mechanical resonance frequency of the structure, the driving voltage of the structure, and the like can be inspected. Also, from these inspection results, it is possible to determine the stress of the structural layer film, the spring constant of the structural body, and the like. Further, since the inspection can be performed without dividing the substrate, it is possible to proceed with the process or repair when a defect is found, thereby improving productivity.

  Note that this embodiment mode can be freely combined with the above embodiment modes.

(Embodiment 5)
In this embodiment, a method for inspecting characteristics of a structure body by performing sacrificial layer etching on a micromachine and a substrate on which the structure body is manufactured will be described. Here, an example in the case of manufacturing a structure having the shape shown in FIG. 11 will be described.

In the step of manufacturing the structure body, first, a first conductive layer 502 to be a fixed electrode is formed over the substrate 501. The first conductive layer 502 is formed by forming a conductive material such as metal or metal oxide using a sputtering method, a CVD method, or the like, and processing the material into an arbitrary shape using a photolithography method or the like. Can be formed. Further, as shown in the drawing, the first conductive layer 502 may be formed directly on the substrate 501, but may be formed on a first protective layer which is a base.

Next, a sacrificial layer 503 is formed over the first conductive layer 502. The sacrificial layer 503 can be formed by forming a material suitable for the sacrificial layer and processing the material into an arbitrary shape. Here, the material suitable for the sacrificial layer refers to, for example, a material that can be removed quickly during sacrificial layer etching, a thick film can be formed in a short time, and processing is easy. Of course, it is also important that the material has a selectivity with respect to other layers when the sacrificial layer is etched. The film thickness of the sacrificial layer 503 is, for example, not less than 0.5 μm and not more than 5 μm (for example, 2 μm).

Next, a second conductive layer 504 to be a movable electrode and a first insulating layer 505 are formed over the sacrificial layer 503. Then, the structure shown in FIG. 11A is formed by processing the second conductive layer and the first insulating layer 505. Here, the second conductive layer and the first insulating layer form a structural layer 506. Note that these structures are examples, and for example, the structural layer can be formed using only the second conductive layer, and the first insulating layer 505 can be formed in multiple layers. That is, it is preferable to apply various shapes and laminated structures to all the layers such as the structural layer, the sacrificial layer, and the fixed electrode depending on the structure of the necessary structure. Note that the thickness of the first insulating layer 505 is, for example, not less than 500 nm and not more than 3 μm (for example, 800 nm).

After the structure is formed as described above, a second protective layer 507 is formed over the first structure 508 that is not used for inspection, as shown in FIG. In FIG. 11, a structure 508 that is not used for inspection is shown on the left side, and a structure 509 for inspection is shown on the right side. As shown in FIG. 11, the second protective layer 507 is not formed over the structure 509 used for inspection.

Next, by performing sacrificial layer etching, as shown in FIG. 11B, only the sacrificial layer included in the structure for inspection is removed, and a space portion 510 is formed. In order to perform the sacrificial layer etching, a sacrificial layer and an etching agent that can take a selective ratio to the second protective layer in addition to the first conductive layer and the structural layer are used.

By forming the inspection structure in this manner, the structure can be inspected in advance on a part of the substrate. The inspection can be performed using the inspection circuit and the inspection method described in the above embodiment. Then, by measuring the height of the space, the pull-down voltage between the first conductive layer and the second conductive layer when a voltage is applied to the structure, the natural frequency of the structural layer, etc., the structural layer It is possible to evaluate the stress of the film, the distortion of the structural layer caused by the stress, the operating voltage of the structure, and the like.

As a result of these inspections, if it is evaluated that the characteristics of the structure are within the range of specification values at the time of design and operate normally, as shown in FIG. 11C, the structure 509 for inspection and the second protective layer 507 is removed. After that, sacrificial layer etching of the structure body 508 is performed, whereby a structure body for manufacturing a micromachine can be formed.

On the other hand, if the structure has poor characteristics and the process proceeds as it is, a defective product can be repaired. For the repair, for example, it is possible to take a means such as removing the structure for inspection, the second protective layer, and the structural layer, and forming the structural layer again.

As described above, according to the present invention, a structure for manufacturing and a structure for inspection can be provided, and the structure can be inspected by performing sacrificial layer etching only on the structure for inspection first. . Thus, by performing inspection after sacrificial layer etching using a structure for inspection, if the characteristics are poor, the structure on the substrate can be repaired, improving productivity. can do.

  Note that this embodiment mode can be freely combined with the above embodiment modes.

(Embodiment 6)
As shown in the fourth embodiment, the inspection circuit includes a power supply circuit and a control circuit, so that the characteristics of a plurality of types of structures can be inspected, or a plurality of the same type of structures can be inspected. it can. In this embodiment mode, such an inspection method will be described with reference to FIGS.

In order to inspect a plurality of structures, for example, an inspection circuit may be configured to have a plurality of structures. Then, electric power and, if necessary, a control signal for controlling the inspection circuit are transmitted from the inspection apparatus, and the inspection circuit operates each structure and outputs its responses sequentially.

An example of an inspection circuit for performing such an inspection is shown in FIG. The inspection circuit 601 includes a wireless communication circuit 602, a control circuit 603, and a plurality of structures 604 to 606.
The wireless communication circuit includes an antenna, a capacitor, the power supply circuit described in Embodiment Mode 4, and the like. The antenna and the capacity communicate with the inspection apparatus, and the power supply circuit generates constant power and supplies power to the circuit.

The control circuit includes a demodulation circuit, a frequency dividing circuit, a driver, and the like, and operates with power supplied from the power supply circuit. The demodulating circuit demodulates the control signal transmitted from the inspection device, and the frequency dividing circuit generates a clock signal having a necessary frequency. In response to the control signal, the driver selects a structure to be inspected and supplies power. The control circuit transmits a response signal from the structure to the wireless communication circuit.

When a circuit for selecting one structure from a plurality of structures is configured by a driver, the control signal may be a start pulse for starting the operation of the driver. Further, this circuit can also be constituted by a decoder instead of a driver, and the control signal in that case is an address signal.

The control circuit having the above configuration sequentially selects and operates a plurality of structures one by one, transmits the response of the structures as an output signal to the wireless communication circuit, and the wireless communication circuit outputs it wirelessly.
The period during which the control circuit selects the structure can be arbitrarily determined according to the configuration of the driver or decoder and the clock signal supplied to them. This selection period is desirably set to a time sufficient for inspection of the structure. In addition, the control circuit can sequentially select the first structure body 604 to the last structure body 606 and perform the inspection, and then return to the first structure body to perform the inspection repeatedly. A structure in which the operation of the circuit is stopped is also possible.

As described above, the control circuit sequentially selects one structure at a time, whereby a plurality of structures included in the inspection circuit can be inspected.

Here, FIG. 12A illustrates a structure in which the wireless communication circuit and the structure are connected to the control circuit and the wireless communication circuit and the structure are not connected. This is because the response signal from the structure is transmitted to the wireless communication circuit via the control circuit as described above. Note that it is also possible to connect the wireless communication circuit and the structure and directly output a response signal from the structure. In addition, the inspection circuit has only one structure, and the control circuit inputs various signals to the structure according to the plurality of inspection items, thereby inspecting one structure with a plurality of items. Is also possible.

In addition, an inspection circuit having a structure different from the above is described with reference to FIG. As shown in the drawing, the inspection circuit 607 includes a wireless communication circuit 608, a control circuit 609, and a structure array 610 in which a plurality of structures are arranged in a matrix. The wireless communication circuit includes an antenna and a power supply circuit similarly to the inspection circuit shown in Embodiment Mode 4 and FIG.

The control circuit 609 can include a driver 611 and a selector 612 for selecting one structure from a plurality of structures, and an IF 613 that transmits a signal of the structure to the wireless communication circuit. The plurality of structures arranged in an array are selected one by one by a driver.

Here, the driver of the control circuit can also include a decoder. That is, the control circuit has a structure in which one (here, a structure) is selected from a plurality, such as a flat panel display and a memory. Then, in the inspection circuit having the above-described configuration, one structure is selected by the control circuit and the response signal is output from the wireless communication circuit, similarly to the inspection circuit shown in FIG.

With such a structure of the inspection circuit, a plurality of structures can be inspected at a time. Here, when the plurality of structures in the inspection circuit are the same type of structure, the same inspection can be performed on the plurality of structures. Further, if there are structures having different configurations in the inspection circuit, it is possible to inspect different inspection items.

In this manner, by configuring an inspection circuit in which an antenna and a structure are connected, characteristics of the structure during and after fabrication can be inspected in a non-contact manner. In addition, the time required to contact the needle and the time required to replace the needle are not required, and the inspection can be performed speedily, so that productivity can be improved. In addition, since the number of structures to be inspected and the number of inspection items can be inspected at a time by measurement by wireless communication, the time required for the inspection can be shortened.

Further, since it is not necessary to perform inspection by contact with a needle using a prober used for general electric characteristic measurement, the positional accuracy at the time of inspection may be large, and the measurer can also perform inspection easily. In addition, unlike a general semiconductor element, the structure is a three-dimensional structure having a space, so that the structure is very likely to be destroyed by contact with the needle. Note that by performing non-contact measurement, there is no possibility of scratching the substrate with the needle, so that the yield can be increased. Furthermore, the substrate can be returned to the process after inspection. This does not need to be discarded and can improve productivity.

  Note that this embodiment mode can be freely combined with the above embodiment modes.

(Embodiment 7)
In this embodiment, a method for inspecting a structure will be described with reference to a manufacturing flow of the structure included in the micromachine illustrated in FIG.

First, a substrate for manufacturing a structure is prepared (step 701), and a manufacturing process up to sacrificial layer etching is performed (step 702). Here, the steps up to the sacrificial layer etching are steps for forming a fixed electrode, a sacrificial layer, and a structural layer on a substrate as described in the above embodiment by applying a general method for manufacturing a semiconductor element.

Next, an inspection for confirming the process so far, typically an inspection of the thickness of the sacrificial layer is performed (step 703). The inspection can be performed by preparing the inspection circuit described in the above embodiment. If a defect is found, repair such as re-deposition can be performed.

Here, when the structural layer is formed by stacking a plurality of layers as shown in FIG. 5B, the thickness of the sacrificial layer may be inspected after all the structural layers are formed. As shown in FIG. 5A, only the conductive layer (second conductive layer) for forming the structural layer may be formed for inspection, and then the insulating layer may be formed to form the structural layer. In this way, by partially forming the structural layer and performing the inspection, it is possible to easily perform repair when the inspection result is incompatible.

In the case of manufacturing a structure body, the sacrificial layer is then removed by sacrificial layer etching. However, as described in the fifth embodiment, the sacrificial layer etching is performed only on the inspection structure body, and the structure body is formed. Can be inspected. Here, a part of the sacrificial layer on the substrate is removed, and the characteristics of the structure, for example, the stress of the film of the structure layer, the distortion of the structure layer resulting therefrom, the operating voltage of the structure, and the like are measured. A check can be made (step 704).

As described above, in the case where a defect is found by performing the inspection in Step 703 and Step 704 before performing the sacrifice layer etching of the structure to be manufactured, the defective portion can be removed and repair can be performed.

When the above inspection is performed and the measurement value is within a range in which the structure can be produced as planned at the time of design, the sacrificial layer is etched and the sacrificial layer is removed to form a space portion of the structure (step 705). ). After the sacrificial layer etching, the space height inspection described in the second embodiment, the operating voltage inspection described in the fourth embodiment, and the like can be performed (step 706). If the inspection confirms that the structure operates normally, the substrate is divided into chips (step 707).

Thereafter, the final product is formed by packaging (step 708), and final inspection is performed (step 709). Only the structure manufactured by the above process may be packaged, and the electrical circuit manufactured in the other and the above structure are put in one package and bonded to be electrically connected. It can also be in the form of a final product.

In general, when a micromachine is manufactured, the structure is not inspected for operation confirmation on the manufacturing substrate, and after the substrate is divided and packaged to produce the final product form, the operation is inspected. Is called. This is because it is difficult to inspect all the structures on the substrate, but the production efficiency is significantly reduced. However, the defect can be repaired by performing the inspection before the sacrificial layer etching as in the series of flows to which the present invention is applied.
If all of the above inspections cannot be performed, the inspection items may be determined as appropriate according to the structure to be manufactured, but productivity can be improved by finding and repairing defects before etching the sacrificial layer or before dividing the substrate as much as possible. Can be improved.

  Note that this embodiment mode can be freely combined with the above embodiment modes.

(Embodiment 8)
In this embodiment, an example in which the micromachine inspection method described in the above embodiment is applied to the micromachine manufacturing method illustrated in FIGS. Here, as shown in FIG. 14A, the micromachine manufactures a structure body 802 and an electric circuit 804 that controls the structure body on different substrates 801 and 803. Then, as shown in FIG. 14B, the substrate is divided to form a chip 805 having a structure and a chip 806 having an electric circuit, and put in the same package as shown in FIG. Electrical bonding is performed by bonding to produce a micromachine 807 in the form of a final product.

First, an example in which a non-defective structure is selected before the substrate is divided by applying the inspection method shown in step 706 in the seventh embodiment will be described. For example, as illustrated in FIG. 15, a structure body 816 for forming a micromachine and a TEG (Test Element Group) 817 for evaluating characteristics of the structure body are manufactured over the same substrate 815.

After the step of manufacturing the structure is completed, the TEG provided on each substrate is inspected. The TEG can be inspected in a non-contact manner by using the inspection circuit described in the above embodiment. For example, in this inspection, several TEGs are inspected in a contact manner, and a non-contact inspection is performed on an inspection circuit that has been confirmed to operate normally. The inspection result can be used as a reference result, and the TEG evaluation can be performed by comparing the inspection result of other TEGs in a non-contact manner with the reference result. Here, based on the contact-type measurement result, an allowable characteristic diagram in the non-contact type measurement may be created and used as a comparison reference.

Then, as shown in FIG. 15B, according to the above evaluation, the substrate is divided into a substrate 818 whose TEG characteristics operate within a normal range and a substrate 819 which is not within the normal range. The substrate 818 that is determined to operate within the normal range of the TEG characteristics is divided into a chip 820 having a structure as shown in FIG. In addition, for the substrate 819 in which the TEG did not operate within the normal range, the characteristics of the manufactured structure may be poor. It is desirable to give management feedback.

The chip 820 having a structure body may be packaged as it is, or an inspection for each chip 820 may be performed. The inspection for each chip can be performed in a non-contact manner in the case of a chip on which an antenna is mounted as in the inspection circuit described in the above embodiment, and in the case of a chip in which an antenna is not mounted You can test with a formula. Then, as shown in FIG. 15D, a micromachine can be manufactured by dividing a chip 821 that has been confirmed to operate normally and a chip 822 that has not been confirmed to operate normally, and packaging only the chip that operates normally. Is possible.

In this manner, it is possible to determine whether or not the structure is normally manufactured in units of substrates and to divide the structure into chips. By inspecting before packaging and selecting a chip having a non-defective structure, the productivity of the micromachine finally produced can be improved.

In addition, a method for inspecting a plurality of structures at a time in a non-contact manner using the inspection circuit described in Embodiment 5 can also be applied. As shown in FIG. 16A, an inspection circuit including a wireless communication circuit 811, a control circuit 812, and a plurality of structures is formed over a substrate 810, and characteristics of all the structures to be manufactured are inspected. By the inspection, the structure on the substrate is evaluated as a structure 813 that operates normally and a structure 814 that does not operate normally. Then, as shown in FIG. 16B, the substrate can be divided into chips, and a chip having a structure that operates normally can be packaged.

Here, when the substrate is divided, the circuit necessary for the inspection is cut off, and only the part (structure) necessary for the product is taken out. For example, the inspection circuit in FIG. 16A includes a wireless communication circuit 811, a control circuit 812, and a plurality of structures. When dicing, the structure is separated from the substrate into a chip. Thus, when a plurality of structures are connected so as to form one circuit, it is necessary to take out individual chips by dividing the substrate. Therefore, it is necessary to design the layout so that only the structure can be taken out by dividing the substrate.

An electric circuit 804 included in the micromachine is manufactured and inspected using an LSI manufacturing technique, and a chip that operates normally is selected and packaged. However, since the structure 802 is not inspected on the manufacturing substrate 801 and the micromachine 807 is inspected after being packaged, the production efficiency is significantly reduced.
However, by applying the measurement method of the present invention as described above, a total number of inspections can be performed on the structure before the micromachine is manufactured. In addition, it is possible to cut the structure into chips by determining whether or not the structure is normally manufactured on a substrate basis. As a result, it is possible to improve production efficiency and speed up micromachine defect inspection.

  Note that this embodiment mode can be freely combined with the above embodiment modes.

(Embodiment 9)
In this embodiment, an example of the method for manufacturing the inspection circuit described in the above embodiment will be described. For example, a method for manufacturing an inspection circuit including an antenna and a structure as described in Embodiment Mode 1 will be described with reference to FIGS. The drawings are cross-sectional views in the order of steps, showing an antenna on the left side and a structure on the right side.

First, as shown in FIG. 17A, a first conductive layer is formed by forming a conductive material (metal, metal oxide, conductive organic substance, or the like) over a substrate 913 and processing it. 915 is formed. The first conductive layer 915 serves as the antenna 902 and the fixed electrode (first conductive layer) of the structure 903. The first conductive layer 915 connects the antenna 902 and the fixed electrode of the structure body 903 (not illustrated). Although the substrate 913 used here may be used as it is, the first conductive layer can be formed after the protective layer 914 is formed. In the figure, the protective layer 914 is formed on the substrate and the first conductive layer is formed thereon. An example in which one conductive layer is formed is shown.

Next, an insulating material (such as silicon oxide, silicon nitride, or an insulating organic material) is formed over the first conductive layer 915 and processed to form the first insulating layer 916. To do.
The first insulating layer 916 serves as a sacrificial layer in the structure body 903, and serves as an interlayer film for insulating the wiring extracted from the center of the antenna in the antenna 902 portion.

Next, as illustrated in FIG. 17B, a conductive second conductive layer 917 and an insulating second insulating layer 918 are formed over the first insulating layer 916 and processed. Thus, the structure layer of the structure is formed. This structural layer may have a single-layer structure including only a conductive layer, but here, a structural layer in which a conductive layer and an insulating layer are stacked is shown.
In addition, although the conductive layer and the insulating layer can be formed and processed separately, here, an example in which the two layers are sequentially formed and then processed at once by self-alignment is shown. This is because processing by self-alignment can reduce the photolithography process and the photomask used in the process. The second conductive layer 917 serves as a movable electrode of the structure body 903 and a wiring for taking out the wiring from the antenna 902 and connecting it to the movable electrode of the structure body.

If the steps up to here are formed, this inspection circuit can be used to perform the inspection described in the above embodiment, for example, the film thickness inspection of the sacrificial layer. In addition, the inspection can be performed even when only the second conductive layer 917 is formed without forming the second insulating layer 918.

Next, as shown in FIG. 17C, a material having a selectivity with respect to the first insulating layer is formed over the second conductive layer and the second insulating layer 918 forming the antenna, and processed. Thus, the protective layer 919 is formed.
This protective layer 919 is a protective layer for not etching the first insulating layer of the antenna portion at the time of sacrificial layer etching for manufacturing the structure 903.

Next, sacrificial layer etching is performed to remove the sacrificial layer, so that the structure 903 having a space portion and the antenna 902 can be formed.
By using the inspection circuit manufactured as described above, the inspection described in the above embodiment, for example, inspection of the height of the space portion, inspection of whether the sacrificial layer is removed, inspection of the operating voltage, or the like is performed. be able to.

An inspection circuit including an antenna and a structure can be manufactured by applying a general method for manufacturing a semiconductor element. For example, film formation can be performed by applying a CVD method, a sputtering method, an evaporation method, or the like, and each film or layer can be processed by a photolithography method and etching. Then, by combining the conductive layer and the insulating layer as described above, an inspection circuit having an antenna and a structure can be formed.

In the above description, the antenna is formed using the first conductive layer, but the antenna can also be formed using the second conductive layer. This example will be described with reference to FIG.

As shown in FIG. 18A, a protective layer 921 is formed over a substrate 920, and a first conductive layer 922 is formed thereover. The first conductive layer 922 forms a fixed electrode of the structure 903 and serves as a wiring connecting the antenna 902 and the fixed electrode.
Next, a first insulating layer 923 is formed over the first conductive layer 922. The first insulating layer 923 serves as a sacrificial layer for the structure 903 and also serves as an interlayer film for insulating a wiring taken out from the center of the antenna in the antenna 902 portion.
Then, the second conductive layer 924 and the second insulating layer 925 are formed over the first insulating layer 923 and processed, whereby the structure layer and the antenna of the structure body are formed. Here, the second conductive layer is a movable electrode of the structure 903, and the antenna and the movable electrode of the structure are connected by the second conductive layer (not illustrated).

A protective layer is formed by forming a material having a selectivity with respect to the first insulating layer over the second conductive layer and the second insulating layer forming the antenna 902 and processing the material. Then, the sacrificial layer is removed by performing sacrificial layer etching, and a structure having a space portion and an antenna can be formed.

However, as shown in FIG. 18B, the sacrificial layer etching is performed without forming the protective layer, and the structure having the space portion 926 is separated from the substrate 920 through the space portion 926. An antenna 902 can be formed. Such an antenna is less susceptible to noise from a conductive layer present on the substrate or the periphery.
By manufacturing the antenna and the structure as described above, a highly sensitive antenna can be obtained, and a highly accurate inspection can be performed. Note that the example of creation given here is merely an example, and an inspection circuit can be produced by various methods.

In the case where the inspection circuit includes a power supply circuit and a control circuit, it is necessary to form a capacitor and a semiconductor element on the same substrate. There are various methods for manufacturing a semiconductor element and a structure body over the same substrate. Here, an example in which a thin film transistor and a structure body are formed over a substrate will be described with reference to FIGS.

First, a method for forming a semiconductor element as shown in FIG.
First, an insulating layer is formed over the substrate 927. The insulating layer is formed of silicon oxide, silicon nitride, or the like. Next, a semiconductor layer 928 is formed over the insulating layer, the semiconductor layer is crystallized by laser crystallization, thermal crystallization using a metal catalyst, or the like, and then processed into a predetermined shape by etching or the like (patterning) )I do. Next, a gate insulating layer is formed so as to cover the semiconductor layer. The gate insulating layer is formed of silicon oxide, silicon nitride, or the like.

Next, the gate electrode layer 929 is formed. The gate electrode layer 929 is formed into a desired shape by forming a conductive layer using a conductive element or compound. In the case of performing patterning by a photolithography method, when the resist mask is etched with plasma or the like, the gate electrode width can be shortened and the performance of the transistor can be improved. Next, an impurity element is added to the semiconductor layer to form an N-type impurity region and a P-type impurity region. The impurity region is formed by forming a resist mask by photolithography and adding an impurity element such as phosphorus, arsenic, or boron. Next, an insulating layer is formed using a nitrogen compound or the like, and the insulating layer is anisotropically etched in the vertical direction, whereby an insulating layer (side wall) in contact with the side surface of the gate electrode is formed. Next, an impurity is added to the semiconductor layer having the N-type impurity region, and a first N-type impurity region immediately below the sidewall, a second N-type impurity region having an impurity concentration higher than that of the first impurity region, Form. Through the above steps, N-type and P-type semiconductor elements 930 are formed.

The semiconductor layer included in the semiconductor element manufactured through the above steps may use any semiconductor such as an amorphous semiconductor, a microcrystalline semiconductor, a nanocrystal semiconductor, a polycrystalline semiconductor, an organic semiconductor, and the like. In order to obtain a semiconductor element having good characteristics, a crystalline semiconductor layer (low-temperature polysilicon layer) crystallized at a temperature of 200 to 600 degrees (preferably 350 to 500 degrees), or a temperature of 600 degrees or more. A crystalline semiconductor layer (high-temperature polysilicon layer) crystallized in (1) can be used. In order to obtain a semiconductor element with better characteristics, a semiconductor layer crystallized using a metal element as a catalyst or a semiconductor layer crystallized by a laser irradiation method may be used. Alternatively, a semiconductor layer formed by a plasma CVD method using a gas containing SiH ₄ and F ₂ , a gas containing SiH ₄ and H ₂ , or the like, or a semiconductor layer that is irradiated with a laser may be used. The semiconductor layer of the semiconductor element in the circuit is preferably formed so as to have a crystal grain boundary extending in parallel with the carrier flow direction (channel length direction). Such an active layer can be formed using a continuous wave laser (which can be abbreviated as CWLC) or a pulse laser operating at 10 MHz or higher, preferably 60 to 100 MHz. The thickness of the semiconductor layer is 20 nm to 200 nm, preferably 50 nm to 150 nm. The semiconductor layer (particularly the channel formation region) has a concentration of 1 × 10 ¹⁹ atoms / cm ³ to 1 × 10 ²² atoms / cm ³ , preferably 1 × 10 ¹⁹ atoms / cm ^{3 to} 5 × 10 ²⁰ atoms. By adding hydrogen or a halogen element at a concentration of / cm ³ , it is possible to obtain an active layer with fewer defects and less cracking.

The semiconductor element manufactured as described above has an S value (subthreshold value) of 0.35 V / dec or less, preferably 0.09 to 0.25 V / dec. Further, the mobility may have a characteristic of 10 cm ² / Vs or higher. Further, the semiconductor element is a ring oscillator that operates at a power supply voltage of 3 to 5 V, and desirably has a characteristic of 1 MHz or more, preferably 10 MHz or more. In addition, the semiconductor element described in this embodiment has a structure in which a semiconductor layer, a gate insulating layer, and a gate electrode layer are sequentially stacked over a substrate. However, the structure is not limited to this example. It is also possible to adopt a structure in which a layer, an insulating film, and a semiconductor layer are sequentially stacked. In this embodiment mode, the N-type semiconductor element has a first N-type impurity region and a second N-type impurity region. However, the present invention is not limited to this example, and the impurity concentration in the impurity region is uniform. There may be.

Further, the semiconductor element may be provided over a plurality of layers. In the case of manufacturing with a multilayer structure, a low dielectric constant material is preferably used as a material for the interlayer insulating film in order to reduce parasitic capacitance between layers. Examples thereof include resin materials such as epoxy resins and acrylic resins, and compound materials made by polymerization of siloxane polymers. If parasitic capacitance is reduced in a multi-layer structure, it is possible to reduce the area, increase the operation speed, and reduce power consumption. In addition, reliability can be improved by providing a protective layer for preventing alkali metal contamination. The protective layer may be provided with an inorganic material such as aluminum nitride or a silicon nitride film so as to wrap the semiconductor element in the circuit or to wrap the entire circuit.

Subsequently, an insulating layer 931 is formed so as to cover the semiconductor element 930. The insulating layer is formed using an insulating inorganic compound, an organic compound, or the like. Next, a contact hole exposing the second N-type impurity region and the P-type impurity region is formed, a conductive layer is formed so as to fill the contact hole, and the conductive layer is patterned into a desired shape. To do. The conductive layer is formed using a conductive metal element, compound, or the like.

Next, an insulating layer 933 is formed so as to cover the conductive layer. The insulating layer 933 is formed using an insulating inorganic compound, an organic compound, or the like. Next, a contact hole for exposing the conductive layer is formed, a conductive layer is formed so as to fill the contact hole, and patterned into a desired shape, whereby the fixed electrode (first conductive layer 934) of the structural layer is formed. Form. The fixed electrode also serves as a wiring connecting the antenna and the fixed electrode.

Next, as illustrated in FIG. 19B, a first insulating layer 935 is formed over the first conductive layer 934. The first insulating layer serves as a sacrificial layer for the structure, and also serves as an interlayer film for insulating the wiring extracted from the center of the antenna in the antenna portion. Then, the second conductive layer 936 and the second insulating layer 937 are formed over the first insulating layer and processed, whereby the structure layer and the antenna of the structure body are formed. Here, the second conductive layer is a movable electrode of the structure, and the antenna and the movable electrode of the structure are connected by the second conductive layer (not shown).
A protective layer is formed by forming a material having a selectivity with respect to the first insulating layer on the second conductive layer and the second insulating layer forming the antenna, and processing the material. Then, the sacrificial layer is removed by performing sacrificial layer etching, so that the structure 903 having a space portion and the antenna 902 can be formed.

Each layer forming the insulating layer, the conductive layer, the semiconductor element, and the structure can be formed using a single-layer structure of a single material or a stacked structure of a plurality of materials.

By manufacturing an inspection circuit having a semiconductor element, an antenna, and a structure as described above and applying the inspection method of the present invention, the structure can be inspected during and after the manufacturing.

The structure manufactured as described above and evaluated as a non-defective product by inspection divides the substrate and is assembled into a micromachine as a chip. Therefore, at the time of dividing the substrate, it is possible to cut off a circuit that is necessary only at the time of inspection and take out only a part necessary for the product.

For example, a case where a structure body is taken out from a test circuit to a chip will be described with reference to FIG. As shown in FIG. 20A, in the case where the inspection circuit 901 includes the antenna 902 and the structure 903, the antenna 902 and the structure 903 are separated from each other at a portion where a wiring 904 connecting them is indicated by a dotted line. 903 can be taken out as a chip for manufacturing a micromachine.

20B, even when the structure 903 and the pad 906 are connected to the inspection circuit 901, wirings 904 and 905 that connect the structure 903, the antenna 902, and the pad 906 are provided. The antenna 902 and the pad 906 can be separated from the structure 903 at a portion indicated by a dotted line, and the structure 903 can be taken out as a chip. In this case, the disconnected wiring 904 is connected to the structure body 903. Note that only the wiring 904 for connecting the structure body 903 and the antenna 902 can be separated, and the pad 906 can be used as a bonding pad for connecting to an electric circuit.

In addition, as shown in FIGS. 12 and 16A, even when the inspection circuit includes peripheral circuits such as a capacitor, a power supply circuit, and a control circuit, the substrate is divided at a wiring portion that connects the structure and the circuit, Only the structure can be taken out as a chip. In this case as well, the peripheral circuit such as the power supply circuit and the control circuit included in the inspection circuit is designed to be incorporated into the micromachine, and the structure and the antenna connected to the peripheral circuit via the wiring are cut out at the wiring portion. It is also possible to package the structure body and the peripheral circuit as a chip and as a micromachine. Note that wiring for connecting the structure and peripheral circuits to the antenna is not necessarily required. For example, the structure body and the peripheral circuit can be directly connected to the antenna without using a wiring. In this case, the antenna is cut out.

Then, the structure 903 separated and separated on the peripheral circuit and the wiring is packaged together with an electric circuit 907 manufactured using another substrate as illustrated in FIG. For example, as shown in the figure, the structure 903 and the electric circuit 907 are joined by wire bonding 909 via pads 908 and 910. Here, an example in which a wire 909 connects to a terminal 911 of a package from a pad 910 provided on a chip having an electric circuit 907 is shown.

Here, an example is shown in which a structure body and an electric circuit are manufactured on separate substrates to form a chip and packaged. However, a structure body and an electric circuit can be manufactured and packaged over the same substrate by applying the semiconductor element manufacturing process described in this embodiment mode. Also at this time, when a plurality of circuits and structures are joined by wiring, similarly to the above, the substrate can be divided at the wiring portion to form each chip for packaging. In addition, the wiring to be cut may be wiring that connects a structure different from the peripheral circuit, such as a power source for applying a common potential at the time of inspection. By laying out the structure so that it is cut at the wiring portion and producing it on the substrate, it is possible to produce a plurality of structures on the same substrate and further inspect the structure on the substrate. Become.

In this manner, by cutting out the structure included in the inspection circuit described in any of the above embodiments at a wiring portion, a micromachine can be manufactured using the inspected structure.
By manufacturing a micromachine in this manner, a structure body that has been confirmed to operate can be packaged, and an electric circuit for packaging together, a package material, and the like are not wasted.

  Note that this embodiment mode can be freely combined with the above embodiment modes.

3A and 3B illustrate a micromachine measuring method according to the present invention. The figure explaining the defect which arises by sacrificial layer etching. The figure explaining the example of a response of a test | inspection circuit. The figure explaining the example of a response of an inspection circuit. 4A and 4B illustrate a micromachine of the present invention. The figure explaining the example of a response of an inspection circuit. 3A and 3B illustrate a micromachine measuring method according to the present invention. 3A and 3B illustrate a micromachine measuring method according to the present invention. FIG. 6 illustrates a power supply circuit. 3A and 3B illustrate a micromachine measuring method according to the present invention. 3A and 3B illustrate a micromachine measuring method according to the present invention. 3A and 3B illustrate a micromachine measuring method according to the present invention. 4A and 4B illustrate a flow for manufacturing a micromachine of the present invention. 8A and 8B illustrate an example of a flow for manufacturing a micromachine of the present invention. 8A and 8B illustrate an example of a flow for manufacturing a micromachine of the present invention. 8A and 8B illustrate an example of a flow for manufacturing a micromachine of the present invention. 4A and 4B illustrate a method for manufacturing a structure body of the present invention. 4A and 4B illustrate a method for manufacturing a structure body of the present invention. 8A and 8B illustrate a method for manufacturing a micromachine of the present invention. 8A and 8B illustrate a method for manufacturing a micromachine of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Inspection apparatus 102 Inspection circuit 103 Input / output interface 104 Control circuit 105 Radio circuit 106 Antenna 107 Substrate 108 Antenna 109 Structure 110 Capacitance 111 Resistance 112 Resistance 113 Property 114 Property 115 Frequency property 116 Frequency property 117 Frequency property 118 Frequency property 118 Frequency property 201 Substrate 202 First conductive layer 203 Sacrificial layer 204 Second conductive layer 205 Layer 206 Spatial portion 207 Portion 208 Frequency characteristic 209 Frequency characteristic 210 Frequency characteristic 211 Remaining sacrificial layer 301 Antenna 302 Structure 303 Measuring pad 304 Resistance 401 Antenna 402 Capacitance 403 Structure 404 Power supply circuit 405 Switching element 406 Control circuit 407 Diode 408 Capacitance 409 Input terminal 410 Output terminal 411 Output terminal 412 Rectifier circuit 413 Regulation 414 Step-up circuit 415 First conductive layer 416 Output terminal 417 Structure layer 418 Second conductive layer 419 Curve 420 Input terminal 421 Input terminal 422 Output terminal

Claims (20)

A method for inspecting a microstructure having a first conductive layer, a second conductive layer, and a sacrificial layer or a space provided between the first conductive layer and the second conductive layer,
Supplying power to the microstructure wirelessly via an antenna connected to the microstructure;
A method for inspecting a microstructure, wherein electromagnetic waves generated from the antenna are detected as characteristics of the microstructure. A method for inspecting a microstructure having a first conductive layer, a second conductive layer, and a sacrificial layer or a space provided between the first conductive layer and the second conductive layer,
The microstructure is connected to a power supply circuit;
Supplying power to the microstructure and the power supply circuit wirelessly via an antenna connected to the microstructure and the power supply circuit;
A method for inspecting a microstructure, wherein electromagnetic waves generated from the antenna are detected as characteristics of the microstructure. A method for inspecting a microstructure having a first conductive layer, a second conductive layer, and a sacrificial layer or a space provided between the first conductive layer and the second conductive layer,
The microstructure is connected to a power supply circuit;
Supplying power to the microstructure and the power supply circuit wirelessly via an antenna connected to the microstructure and the power supply circuit;
An inspection method for a microstructure, wherein electromagnetic waves generated from the antenna are detected as characteristics of the microstructure and the power supply circuit. A method for inspecting a microstructure having a first conductive layer, a second conductive layer, and a sacrificial layer or a space provided between the first conductive layer and the second conductive layer,
The microstructure is connected to a control circuit;
The control circuit is connected to a power supply circuit,
At least one of the microstructure, the control circuit, and the power supply circuit is connected to an antenna;
Supplying power to the microstructure, the control circuit, and the power supply circuit wirelessly through the antenna connected to at least one of the microstructure, the control circuit, and the power supply circuit;
A method for inspecting a microstructure, wherein electromagnetic waves generated from the antenna are detected as characteristics of the microstructure. A method for inspecting a microstructure having a first conductive layer, a second conductive layer, and a sacrificial layer or a space provided between the first conductive layer and the second conductive layer,
The first conductive layer is connected to a first pad;
The second conductive layer is connected to a second pad;
Supplying power to the microstructure from the first pad and the second pad;
An inspection method for a microstructure, wherein an electromagnetic wave generated from an antenna connected to the microstructure is detected as a characteristic of the microstructure. A method for inspecting a microstructure having a first conductive layer, a second conductive layer, and a sacrificial layer or a space provided between the first conductive layer and the second conductive layer,
The first conductive layer is connected to a first pad;
The second conductive layer is connected to a second pad;
Supplying power to the microstructure wirelessly via an antenna connected to the microstructure;
Inspecting a microstructure, wherein a voltage applied to the microstructure or a current flowing through the microstructure is detected from the first pad and the second pad as a characteristic of the microstructure. Method. A first microstructure including a first conductive layer, a second conductive layer, and a sacrificial layer or a space provided between the first conductive layer and the second conductive layer is connected to the antenna. And
A second microstructure having the same structure as the first microstructure is provided adjacent to the first microstructure;
Supplying power to the first microstructure wirelessly via the antenna;
A method for inspecting a micro structure, wherein an electromagnetic wave generated from the antenna is detected as a characteristic of the first micro structure, and the characteristic of the second micro structure is evaluated.   8. The frequency or intensity of the power is changed according to claim 1, and the intensity of electromagnetic waves generated from the antenna is detected as the characteristic in relation to the change in frequency or intensity of the power. A method for inspecting a micro structure characterized by the above. A method for inspecting a microstructure having a first conductive layer, a second conductive layer, and a sacrificial layer or a space provided between the first conductive layer and the second conductive layer,
The first conductive layer is connected to a first pad;
The second conductive layer is connected to a second pad;
Supplying power to the microstructure from the first pad and the second pad;
A method for inspecting a microstructure, wherein a current flowing through the microstructure is detected as a characteristic of the microstructure.   10. The microstructure inspection method according to claim 9, wherein a frequency or intensity of the electric power is changed, and a current flowing through the microstructure is detected as the characteristic in relation to the change of the frequency or intensity.   11. The characteristic according to claim 1, wherein the characteristics include a film thickness of the sacrificial layer, a height of the space portion, presence or absence of the sacrificial layer, a spring constant of the microstructure, and the microstructure. A method for inspecting a microstructure, which is a resonance frequency of the body or a driving voltage for the microstructure. A first conductive layer, a second conductive layer, and a sacrificial layer or a space portion provided between the first conductive layer and the second conductive layer, the first having a known characteristic The microstructure is connected to the first antenna;
A second microstructure having the same structure as the first microstructure is connected to a second antenna having the same structure as the first antenna;
Supplying power to the first microstructure wirelessly via the first antenna;
Detecting electromagnetic waves generated from the first antenna to be a reference characteristic of the second microstructure,
Supplying power to the second microstructure wirelessly via the second antenna;
Detecting an electromagnetic wave generated from the second antenna as a characteristic of the second microstructure,
A method for inspecting a micro structure, wherein the characteristic of the second micro structure is evaluated by comparing the detected characteristic of the second micro structure with the reference characteristic.   13. The method according to claim 12, wherein the frequency or intensity of the electric power is changed, and the intensity of electromagnetic waves generated from the first antenna and the second antenna is detected as the characteristic in relation to the change or intensity of the frequency. A method for inspecting a featured micro structure. 14. The characteristic according to claim 12, wherein the characteristics include a film thickness of the sacrificial layer, a height of the space portion, presence or absence of the sacrificial layer, a spring constant of the first microstructure, and the first micro A method for inspecting a microstructure, which is a resonance frequency of the structure or a driving voltage of the first microstructure. In any one of claims 12 to 14, the characteristics include the thickness of the sacrificial layer, the height of the space, the presence or absence of the sacrificial layer, the spring constant of the second microstructure, A method for inspecting a microstructure, which is a resonance frequency of the second microstructure or a driving voltage for the second microstructure.   16. The method for inspecting a microstructure according to claim 12, wherein the first microstructure and the second microstructure are provided on the same substrate. .   16. The method for inspecting a microstructure according to claim 12, wherein the first microstructure and the second microstructure are provided on different substrates. .   The method for inspecting a microstructure according to claim 1, wherein the space portion is a region formed by removing the sacrificial layer.   The method for inspecting a microstructure according to claim 1, wherein the first conductive layer and the second conductive layer are provided in parallel. A micromachine having a microstructure inspected using the inspection method according to any one of claims 1 to 19 and an electric circuit connected to the microstructure.

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